1. Field of the Invention
The present invention relates to friction pressure reducers for use in aqueous treating fluids.
2. Description of the Prior Art
In the drilling, completion and stimulation of oil and gas wells, aqueous well treating fluids are often pumped through tubular goods disposed in well bores. In order to reduce the friction between the aqueous treating fluid and the tubular goods during pumping whereby the pressure at the pump is reduced, friction pressure reducing additives have heretofore been combined with the aqueous treating fluids.
For example, a treatment commonly utilized for stimulating hydrocarbon production from a subterranean zone penetrated by a well bore is hydraulic fracturing. In most hydraulic fracturing treatments, an aqueous treating fluid referred to in the art as a pad fluid is pumped through tubular goods disposed in the well bore into the subterranean zone to be stimulated at a rate and pressure such that fractures are formed and extended in the subterranean zone. Thereafter, a viscosified aqueous fluid having proppant particles suspended therein is pumped into the fractures so that the proppant particles suspended therein are deposited in the fractures when the viscous aqueous fluid is broken and recovered. The proppant particles function to prevent the fractures from closing whereby conductive channels are formed through which produced fluids can flow to the well bore.
While the aqueous pad fluids and other aqueous well treating fluids containing friction pressure reducers utilized heretofore have been used successfully, the friction pressure reducers have been suspended in a hydrocarbon-water emulsion and as a result they have been toxic and detrimental to the environment. Thus, there are needs for improved friction pressure reducers which are non-toxic and environmentally acceptable.
The present invention provides improved methods of treating subterranean zones penetrated by well bores, improved aqueous well treating fluids and non-toxic environmentally acceptable friction reducers which meet the needs described above and overcome the deficiencies of the prior art. A method of this invention for treating a subterranean zone penetrated by a well bore comprises the following steps. An aqueous treating fluid that comprises water and a non-toxic environmentally acceptable friction pressure reducer is prepared or provided. The friction pressure reducer comprises a mixture of a copolymer of acrylamide and dimethylaminoethyl acrylate quaternized with benzyl chloride and a stabilizing and dispersing homopolymer of ethanaminium,N,N,N-trimethyl-2-[(1,oxo-2-propenyl)oxy]-chloride. Thereafter, the aqueous treating fluid is pumped into the subterranean zone.
An aqueous well treating fluid of this invention is basically comprised of water and a non-toxic environmentally acceptable friction pressure reducer comprising a mixture of a copolymer of acrylamide and dimethylaminoethyl acrylate quaternized with benzyl chloride and a stabilizing and dispersing homopolymer of ethanaminium,N,N,N-methyl-2-[(1,oxo-2-propenyl)oxy]-chloride.
A non-toxic environmentally acceptable water friction pressure reducer of this invention comprises a mixture of a copolymer of acrylamide and dimethylaminoethyl acrylate quaternized with benzyl chloride and a stabilizing and dispersing homopolymer of ethanaminium,N,N,N-trimethyl-2-[(1,oxo-2-propenyl)oxy]-hloride.
The objects, features and advantages of the present invention will be readily parent to those skilled in the art upon a reading of the description of preferred embodiments which follows.